Production method for polyester copolymer comprising recycled monomers

Abstract

The present disclosure relates to a method for preparation of a polyester copolymer including recycled monomers, and to a method for preparation of a polyester copolymer having excellent quality while using recycled monomers.

What is claimed is: 
     
         1 . A method for preparation of a polyester copolymer comprising:
 1) preparing a recycled bis-2-hydroxyethyl terephthalate solution by dissolving recycled bis-2-hydroxyethyl terephthalate in water or ethylene glycol (step 1);   2) preparing an oligomer by an esterification reaction of the recycled bis-2-hydroxyethyl terephthalate solution, a dicarboxylic acid or its derivative, and a diol containing ethylene glycol and a comonomer (step 2); and   3) preparing a polyester copolymer by a polycondensation reaction of the oligomer (step 3),   wherein a molar ratio of the diol and the dicarboxylic acid or its derivative is 0.2:1 to 1.35:1.   
     
     
         2 . The method of  claim 1 ,
 wherein a concentration of the recycled bis-2-hydroxyethyl terephthalate solution is 25 to 99 wt %.   
     
     
         3 . The method of  claim 1 ,
 wherein the recycled bis-2-hydroxyethyl terephthalate is dissolved in water at 25 to 100° C. in step 1.   
     
     
         4 . The method of  claim 1 ,
 wherein the recycled bis-2-hydroxyethyl terephthalate is dissolved in ethylene glycol at 25 to 197° C. in step 1.   
     
     
         5 . The method of  claim 1 ,
 wherein the dicarboxylic acid or its derivative is terephthalic acid, dimethyl terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl dicarboxylic acid, 4,4′-stilbenedicarboxylic acid, 2,5-furandicarboxylic acid, or 2,5-thiophenedicarboxylic acid.   
     
     
         6 . The method of  claim 1 ,
 wherein the comonomer is cyclohexanedimethanol, or isosorbide.   
     
     
         7 . The method of  claim 1 ,
 wherein a molar ratio of the comonomer and ethylene glycol is 0.1:1 to 20:1 in step 2.   
     
     
         8 . The method of  claim 1 ,
 wherein the step 2 is performed at a pressure of 0.1 to 3.0 kg/cd and a temperature of 200 to 300° C.   
     
     
         9 . The method of  claim 1 ,
 wherein the step 2 is performed for 2 hours to 10 hours.   
     
     
         10 . The method of  claim 1 ,
 wherein the step 3 is performed at a temperature of 240 to 300° C. and a pressure of 400 to 0.01 mmHg.   
     
     
         11 . The method of  claim 1 ,
 wherein the step 3 is performed for 1 hour to 10 hours.   
     
     
         12 . The method of  claim 1 ,
 wherein the prepared polyester copolymer comprises 1 to 80 wt % of the residue of the recycled bis-2-hydroxyethyl terephthalate.   
     
     
         13 . The method of  claim 1 ,
 wherein the prepared polyester copolymer has an intrinsic viscosity of 0.50 to 1.0 dl/g.